Multi-direction wiring for replacement gate lines

ABSTRACT

A post-planarization recess etch process is employed in combination with a replacement gate scheme to enable formation of multi-directional wiring in gate electrode lines. After formation of disposable gate structures and a planarized dielectric layer, a trench extending between two disposable gate structures are formed by a combination of lithographic methods and an anisotropic etch. End portions of the trench overlap with the two disposable gate structures. After removal of the disposable gate structures, replacement gate structures are formed in gate cavities and the trench simultaneously. A contiguous gate level structure can be formed which include portions that extend along different horizontal directions.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.13/897,568, filed May 20, 2013 the entire content and disclosure ofwhich is incorporated herein by reference.

BACKGROUND

The present disclosure generally relates to semiconductor structures,and particularly to a semiconductor structure including multi-directionwiring for replacement gate lines, and methods of manufacturing thesame.

The difficulty of printing gate patterns for technologies with a smallpitch on par with lithographic minimum dimensions has led to thedevelopment of unidirectional gate patterns, i.e., gate patterns thatextend only along a single horizontal direction, and prohibits extensionof the gate lines in any other horizontal direction. Unidirectional gatepatterns shifts the burden of signal routing to metal interconnectstructures provided above the gate level, e.g., by requiring morelateral connections to be formed in contact level metal interconnectstructures and/or wiring level metal interconnect structures.

SUMMARY

A post-planarization recess etch process is employed in combination witha replacement gate scheme to enable formation of multi-directionalwiring in gate electrode lines. After formation of disposable gatestructures and a planarized dielectric layer, a trench extending betweentwo disposable gate structures are formed by a combination oflithographic methods and an anisotropic etch. End portions of the trenchoverlap with the two disposable gate structures. After removal of thedisposable gate structures, replacement gate structures are formed ingate cavities and the trench simultaneously. A contiguous gate levelstructure can be formed which include portions that extend alongdifferent horizontal directions.

According to an aspect of the present disclosure, a semiconductorstructure includes a semiconductor material portion located on asubstrate, which contains a source region, a drain region, and a bodyregion. A planarization dielectric layer overlies the semiconductormaterial portion. The semiconductor structure further includes a gatestack structure embedded in the planarization dielectric layer andincluding a gate dielectric and a gate electrode that is embedded in thegate dielectric. The gate dielectric includes a horizontal portion incontact with the body region. The gate dielectric may also include avertical portion having outer sidewalls that define a lateral extent ofthe gate stack structure. The gate stack structure includes a firstportion contacting the semiconductor material portion and extendingalong a first horizontal direction and a second portion extending alonga second horizontal direction that is different from the firstdirection.

According to another aspect of the present disclosure, a method offorming a semiconductor structure is provided. At least onesemiconductor material portion is formed on a substrate. At least onedisposable gate structure is formed over the at least one semiconductormaterial portion. A planarization dielectric layer is formed over the atleast one semiconductor material portion and the at least one disposablegate structure. A trench is formed in the planarization dielectriclayer. A sidewall of a remaining portion of one of the at least onedisposable gate structure is physically exposed within the trench. Atleast one gate cavity is formed by removing the at least one disposablegate structure. A replacement gate stack structure is formed in the atleast one gate cavity and the trench.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1A is a top-down view of a first exemplary semiconductor structureafter lithographic patterning of a first photoresist layer over asemiconductor-on-insulator (SOI) substrate according to a firstembodiment of the present disclosure.

FIG. 1B is a vertical cross-sectional view of the first exemplarysemiconductor structure along the vertical plane B-B′ of FIG. 1A.

FIG. 2A is a top-down view of the first exemplary semiconductorstructure after formation of a plurality of semiconductor fins bypatterning a top semiconductor layer of the SOI substrate according tothe first embodiment of the present disclosure.

FIG. 2B is a vertical cross-sectional view of the first exemplarysemiconductor structure along the vertical plane B-B′ of FIG. 2A.

FIG. 3A is a top-down view of the first exemplary semiconductorstructure after formation of a plurality of disposable gate structuresaccording to the first embodiment of the present disclosure.

FIG. 3B is a vertical cross-sectional view of the first exemplarysemiconductor structure along the vertical plane B-B′ of FIG. 3A.

FIG. 4A is a top-down view of the first exemplary semiconductorstructure after formation of gate spacers according to the firstembodiment of the present disclosure.

FIG. 4B is a vertical cross-sectional view of the first exemplarysemiconductor structure along the vertical plane B-B′ of FIG. 4A.

FIG. 5A is a top-down view of the first exemplary semiconductorstructure after deposition and planarization of a planarizationdielectric layer according to the first embodiment of the presentdisclosure.

FIG. 5B is a vertical cross-sectional view of the first exemplarysemiconductor structure along the vertical plane B-B′ of FIG. 5A.

FIG. 6A is a top-down view of the first exemplary semiconductorstructure after application and lithographic patterning of a thirdphotoresist layer, and transfer of the pattern in the third photoresistlayer into at least an upper portion of the planarization dielectriclayer and upper portions of disposable gate structures and gate spacersaccording to the first embodiment of the present disclosure.

FIG. 6B is a vertical cross-sectional view of the first exemplarysemiconductor structure along the vertical plane B-B′ of FIG. 6A.

FIG. 6C is a vertical cross-sectional view of the first exemplarysemiconductor structure along the vertical plane C-C′ of FIG. 6A.

FIG. 7A is a top-down view of the first exemplary semiconductorstructure after removal of disposable gate structures according to thefirst embodiment of the present disclosure.

FIG. 7B is a vertical cross-sectional view of the first exemplarysemiconductor structure along the vertical plane B-B′ of FIG. 7A.

FIG. 7C is a vertical cross-sectional view of the first exemplarysemiconductor structure along the vertical plane C-C′ of FIG. 7A.

FIG. 8A is a top-down view of the first exemplary semiconductorstructure after formation of replacement gate stack structures accordingto the first embodiment of the present disclosure.

FIG. 8B is a vertical cross-sectional view of the first exemplarysemiconductor structure along the vertical plane B-B′ of FIG. 8A.

FIG. 8C is a vertical cross-sectional view of the first exemplarysemiconductor structure along the vertical plane C-C′ of FIG. 8A.

FIG. 9A is a top-down view of the first exemplary semiconductorstructure after formation of a contact-level dielectric layer andcontact via structures according to the first embodiment of the presentdisclosure.

FIG. 9B is a vertical cross-sectional view of the first exemplarysemiconductor structure along the vertical plane B-B′ of FIG. 9A.

FIG. 9C is a vertical cross-sectional view of the first exemplarysemiconductor structure along the vertical plane C-C′ of FIG. 9A.

FIG. 10 is a vertical cross-sectional view of a second exemplarysemiconductor structure according to a second embodiment of the presentdisclosure.

FIG. 11 is a vertical cross-sectional view of a third exemplarysemiconductor structure according to the third embodiment of the presentdisclosure.

DETAILED DESCRIPTION

As stated above, the present disclosure relates to a semiconductorstructure including multi-direction wiring for replacement gate lines,and methods of manufacturing the same. Aspects of the present disclosureare now described in detail with accompanying figures. Like andcorresponding elements mentioned herein and illustrated in the drawingsare referred to by like reference numerals. The drawings are notnecessarily drawn to scale. As used herein, ordinals are employed merelyto distinguish similar elements, and different ordinals may be employedto designate a same element in the specification and/or claims.

Referring to FIGS. 1A and 1B, a first exemplary semiconductor structureaccording to a first embodiment of the present disclosure includes asubstrate 8 and a first photoresist layer 37 formed thereupon. At leasta topmost portion of the substrate 8 includes a semiconductor material.The substrate 8 can be a semiconductor-on-insulator (SOI) substrate, abulk substrate, or a hybrid substrate including a bulk portion and anSOI portion.

In one embodiment, the substrate 8 can be an SOI substrate including astack, from bottom to top, of a handle substrate 10, a buried insulatorlayer 20, and a top semiconductor layer 30L. The handle substrate 10 caninclude a semiconductor material, a conductive material, or a dielectricmaterial, and provides mechanical support to the buried insulator layer20 and the top semiconductor layer 30L. The thickness of the handlesubstrate 10 can be from 50 microns to 2 mm, although lesser and greaterthicknesses can also be employed. The buried insulator layer 20 includesa dielectric material such as silicon oxide, silicon nitride, siliconoxynitride or a combination thereof. The thickness of the buriedinsulator layer 20 can be from 10 nm to 1,000 nm, although lesser andgreater thicknesses can also be employed.

The top semiconductor layer 30L includes a semiconductor material, whichcan be an elemental semiconductor material such as silicon or germanium,an alloy of at least two elemental semiconductor materials such as asilicon-germanium alloy, a compound semiconductor material, or any othersemiconductor material known in the art. The thickness of the topsemiconductor layer 30L can be from 30 nm to 600 nm, although lesser andgreater thicknesses can also be employed. The top semiconductor layer30L can include a single crystalline semiconductor material, apolycrystalline semiconductor material, or an amorphous semiconductormaterial. Various portions of the top semiconductor layer 30L may bedoped with electrical dopants, such as p-type dopants or n-type dopants,as needed. Different portions of the top semiconductor layer 30L mayinclude different semiconductor materials. In one embodiment, the topsemiconductor layer 30L includes a single crystalline semiconductormaterial such as single crystalline silicon and/or a single crystallinesilicon-germanium alloy.

While the present disclosure is described employing an SOI substrate,embodiments employing a bulk substrate or a hybrid substrate including abulk portion and an SOI portion are expressly contemplated herein.

The first photoresist layer 37 can be applied over the top semiconductorlayer 30L and is lithographically patterned with a first pattern. Thefirst pattern can be a line and space pattern in which each line extendsalong a horizontal direction, which is herein referred to as a findirection. In one embodiment, the first pattern can include a pluralityof material portions of the first photoresist layer 37 such that each ofthe plurality of material portions extends along a lengthwise direction.As used herein, a “lengthwise direction” of an object refers to adirection about which the moment of inertia of the object becomes theminimum.

In one embodiment, each of the plurality of material portions of thefirst photoresist layer 37 as patterned can have a same lengthwisedirection, which is the fin direction. In one embodiment, each of theplurality of material portions of the first photoresist layer 37 canhave a same width, which is the dimension along a horizontal directionthat is perpendicular to the lengthwise direction. In one embodiment,each of the plurality of material portions of the first photoresistlayer 37 as patterned can have a rectangular cross-sectional area suchthat the lengthwise edges of the rectangle representing thecross-sectional area are parallel to the lengthwise direction. In oneembodiment, the width of each of the plurality of material portions ofthe first photoresist layer 37 as patterned can be a minimumlithographically printable dimension, i.e., a critical dimension, whichis about 32 nm as of 2013.

The plurality of material portions of the first photoresist layer 37 canbe laterally spaced along the widthwise direction of the first pattern,which is a horizontal direction perpendicular to the lengthwisedirection of the first pattern. The lengthwise direction of the firstpattern is the lengthwise direction of the plurality of materialportions of the first photoresist layer 37.

In an alternate embodiment, layer 37 may be a masking layer generatedusing pitch double techniques such as Sidewall Image Transfer (SIT), andmay have dimensions from about 4 nm to 30 nm, and pitches from about 10nm to 60 nm. Pitch doubling techniques such as SIT including a mandrel,spacer, and cut process, are not described here, but are well known inthe art.

Referring to FIGS. 2A and 2B, the first pattern is transferred into atop portion of the substrate 8 to form at least one semiconductormaterial portion. The at least one semiconductor material portion can bea plurality of semiconductor material portions. In one embodiment, theplurality of semiconductor material portions can be a plurality ofsemiconductor fins 30. If the substrate 8 is an SOI substrate, the firstpattern can be transferred through the top semiconductor layer 30L by ananisotropic etch employing the first photoresist layer 37 as an etchmask. The buried insulator layer 20 can be employed as a stopping layerfor the anisotropic etch. The plurality of semiconductor fins 30 can beformed directly on the top surface of the buried insulator layer 20. Ifthe substrate 8 is a bulk substrate, semiconductor fins formed by ananisotropic etch can be electrically isolated by forming shallow trenchisolation structures (not shown) including a dielectric material and/orby forming doped wells that can be employed to form reverse biased p-njunctions. Each semiconductor fin 30 laterally extends along the findirection, which is the lengthwise direction of the semiconductor fin30.

Referring to FIGS. 3A and 3B, disposable gate level layers can bedeposited on the substrate 8 as blanket layers, i.e., as unpatternedcontiguous layers. The disposable gate level layers can include, forexample, a vertical stack of a gate dielectric layer, a disposable gatematerial layer, and a disposable gate cap dielectric layer. Thedisposable gate dielectric layer can be, for example, a layer of siliconoxide, silicon nitride, silicon oxynitride, or halfnium oxide. Thethickness of the gate dielectric layer can be from 1 nm to 10 nm,although lesser and greater thicknesses can also be employed. The gatedielectric layer may be disposable or may be retained when the rest ofthe disposable gate stack removed. The disposable gate material layerincludes a material that can be subsequently removed selective to thedielectric material of a planarization dielectric layer to besubsequently formed. For example, the disposable gate material layer caninclude a semiconductor material such as a polycrystalline semiconductormaterial or an amorphous semiconductor material. The thickness of thedisposable gate material layer can be from 30 nm to 300 nm, althoughlesser and greater thicknesses can also be employed. The disposable gatecap dielectric layer can include a dielectric material such as siliconoxide, silicon nitride, or silicon oxynitride. The thickness of thedisposable gate cap dielectric layer can be from 3 nm to 30 nm, althoughlesser and greater thicknesses can also be employed. Any otherdisposable gate level layers can also be employed provided that thematerial(s) in the disposable gate level layers can be removed selectiveto a planarization dielectric layer to be subsequently formed.

The disposable gate level layers can be lithographically patterned toform disposable gate structures. In one embodiment, a photoresist (notshown) is applied over the topmost surface of the disposable gate levellayers and is lithographically patterned by lithographic exposure anddevelopment. In an alternate embodiment, a masking layer generated usingpitch double techniques such SIT is used to generate gate patterns, thegate pattern in the photoresist or masking layer is transferred into thedisposable gate level layers by an etch, which can be an anisotropicetch such as a reactive ion etch. The remaining portions of thedisposable gate level layers after the pattern transfer constitutedisposable gate structures.

Each disposable gate stack may include, for example, a stack of a gatedielectric portion 40, a disposable gate material portion 42, and adisposable gate cap portion 49. Each disposable gate stack (40, 42, 49)can straddle one or more of the plurality of semiconductor fins 30. Eachdisposable gate stack (40, 42, 49) can extend along a lengthwisedirection, which is different from the fin direction. In one embodiment,a plurality of the disposable gate stacks (40, 42, 49) can extend alonga same horizontal lengthwise direction, which is herein referred to as afirst horizontal direction, or a first direction. In one embodiment, thefirst horizontal direction can be perpendicular to the fin direction.Each disposable gate stack (40, 42, 49) can have a pair of verticalsidewalls that extend along the first horizontal direction.

Referring to FIGS. 4A and 4B, gate spacers 56 can be formed on sidewallsof each of the disposable gate structures (40, 42, 49), for example, bydeposition of a conformal dielectric material layer and an anisotropicetch. The conformal dielectric material layer includes a dielectricmaterial such as silicon oxide, silicon nitride, silicon oxynitride, ora combination. Horizontal portions of the conformal dielectric materiallayer are removed by the anisotropic etch. An overetch can be employedto remove vertical portions of the conformal dielectric material layerfrom portions of sidewalls of the plurality of semiconductor fins 30that are laterally spaced from the disposable gate stacks (40, 42, 49)by a lateral distance greater than the thickness of the conformaldielectric material layer. Remaining vertical portions of the conformaldielectric material layer constitute the gate spacers 56. The gatespacers 56 can contact the top surface of the buried insulator layer 20,i.e., can be formed directly on the top surface of the buried insulatorlayer 20.

Each gate spacer 56 laterally surrounds a disposable gate structure (40,43, 49). Each gate spacer 56 can be topologically homeomorphic to atorus, i.e., can be continuously stretched without creating ordestroying a hole into a torus. As used herein, two objects are“topologically homeomorphic” to each other if a continuous mapping and acontinuous inverse mapping exists between two objects such that eachpoint in one object corresponds to a distinct and unique point inanother object. As used herein, a “continuous” mapping refers to amapping that does not create or destroy a singularity.

Ion implantations can be employed to form various source/drain regions36. As used herein, “source/drain regions” collectively refer to sourceregions and drain regions. Unimplanted portions of each semiconductorfin 30 are herein referred to as body regions 32. A p-n junction, a p-ijunction, or an n-i junction can be formed between each neighboring pairof a source/drain region 36 and a body region 32. As used herein, a “p-ijunction” is a junction between a p-doped region and an intrinsicregion. As used herein, an “n-i junction” is a junction between ann-doped region and an intrinsic region. As used herein, an intrinsicregion refers to an intrinsic portion of a semiconductor material, whichdoes not include externally introduced electrical dopants such as p-typedopants or n-type dopants.

Referring to FIGS. 5A and 5B, a dielectric material layer can bedeposited over the semiconductor fins (32, 36, 36′) and the disposablegate structures (40, 42, 49). The deposited dielectric material layer isherein referred to as a planarization dielectric layer 60. Theplanarization dielectric layer 60 includes a dielectric material, whichcan be, for example, doped or undoped silicon oxide, silicon nitride,silicon oxynitride, or a combination thereof. In one embodiment, theplanarization dielectric layer 60 includes silicon oxide. Theplanarization dielectric layer 60 can be deposited, for example, bychemical vapor deposition (CVD). The thickness of the planarizationdielectric layer 60 as deposited can be controlled such that allportions of the top surface of the planarization dielectric layer 60 arelocated at, or above, top surfaces of the disposable gate cap portions49 that are most proximal to the buried insulator layer 20.

The planarization dielectric layer 60 is subsequently planarized toprovide a planar dielectric surface 63, for example, by chemicalmechanical planarization (CMP). In one embodiment, upper portions of thedisposable gate cap portion 49 can be employed as an endpoint layerduring the planarization. An over-polish may be performed during theplanarization so that the upper portions of each disposable gate capportion 49 can be removed. The planarization dielectric layer 60 issubsequently planarized such that each top surface of a disposable gatecap portion 49 is physically exposed. After the planarization of theplanarization dielectric layer 60, the planar dielectric surface 63 ofthe planarization dielectric layer 60 can be coplanar with each topsurface of the disposable gate cap portions 49.

Referring to FIGS. 6A, 6B, and 6C, a third photoresist layer 77 can beapplied over the planarization dielectric layer 60, and islithographically patterned to form at least one opening therein. Thelocation of each of the at least one opening can be selected in regionsin which an additional conductive connection is desired among the wiringpattern provided by the disposable gate stack (40, 42, 49). The patternin the third photoresist layer 77 is subsequently transferred into atleast an upper portion of the planarization dielectric layer 60 andupper portions of the disposable gate structures (40, 42, 49) and gatespacers 56 by an etch, which can be an anisotropic etch such as areactive ion etch. A trench 69 is formed in the planarization dielectriclayer 60 within each area of an opening in the third photoresist layer77. At least one sidewall of a remaining portion of each disposable gatestructure (40, 42, 49) is physically exposed within the trench 69.

Sidewalls of the trench 69 may be substantially vertical, or can betapered. In one embodiment, all sidewalls of the trench 69 can besubstantially vertical. As used herein, a surface is “substantiallyvertical” if a vertical plane exists from which the surface deviates bynot more than three times the root-mean-square roughness of the surface.In one embodiment, the trench 69 can extend between two disposable gatestructures (40, 42, 49), and sidewalls of remaining portions of the twodisposable gate structures (40, 42, 49) can be physically exposed withinthe trench 69. In another embodiment, the trench 69 can extend from adisposable gate structure (40, 42, 49) and does not extend to any otherdisposable gate structure (40, 42, 49), and sidewalls of a remainingportion of a disposable gate structure (40, 42, 49) can be physicallyexposed within the trench 69. In yet another embodiment, the trench 69can extend among at least three disposable gate structures (40, 42, 49).

In one embodiment, the plurality of disposable gate structures (40 42,49) can extend along the first horizontal direction, and the trench 69can extend along a lateral direction that is different from the firsthorizontal direction. The lateral direction along which the trenchextends is herein referred to as a second horizontal direction, or asecond direction.

In one embodiment, at least an upper portion of at least one gate spacer56 can be removed during the forming of the trench 69. In oneembodiment, the area of the trench 69 can be selected such that thetrench 69 does not overlie any semiconductor material portion over theburied insulator layer 20 (such as the semiconductor fins (32, 36, 36′)and is laterally offset from the semiconductor material portions.

In one embodiment, the bottom surface of the trench 69 can include arecessed surface of the planarization dielectric layer 60. In oneembodiment, the bottom surface of the trench 69 can be located above thetop surface of the buried insulator layer 20. In another embodiment, thebottom surface of the trench 69 can be coplanar with the top surface ofthe buried insulator layer 20. In yet another embodiment, the bottomsurface of the trench 69 can be recessed below the top surface of theburied insulator layer 20. The third photoresist layer 77 issubsequently removed, for example, by ashing.

Referring to FIGS. 7A, 7B, and 7C, the disposable gate structures (40,42, 49) can be partially or completely removed selective to thedielectric material of the planarization dielectric layer 60 andselective to the semiconductor material of semiconductor materialportions (such as the semiconductor fins (32, 36, 36′) above the buriedinsulator layer 20. A gate cavity 59 is formed in each space from whicha disposable gate structure (40, 42, 49) is removed. Each trench 69 iscontiguous with at least one gate cavity 59. In one embodiment, a trench69 can be contiguous with two gate cavities 59. In another embodiment, atrench 69 can be contiguous with one gate cavity 59. In yet anotherembodiment, a trench 69 can be contiguous with at least three gatecavities 59.

Referring to FIGS. 8A, 8B, and 8C, the gate cavities 59 and thetrench(es) 69 can be filled with a gate stack which might include adielectric layer and a must include a conductive material layer. Thegate dielectric layer can include a dielectric metal oxide, a dielectricsemiconductor oxide, or a combination thereof. In one embodiment, thegate dielectric layer can be deposited by a conformal deposition methodsuch as atomic layer deposition (ALD) and/or chemical vapor deposition(CVD). In this case, all vertical portions of the gate dielectric layercan have a same thickness t. In one embodiment, horizontal portions ofthe gate dielectric layer can also have the thickness t.

Excess portions of the conductive material layer can be removed fromabove the top surface of the planarization dielectric layer 60, forexample, by planarization. For example, chemical mechanicalplanarization (CMP) can be employed to remove the portions of theconductive material layer from above the top surface of theplanarization dielectric layer 60. Portions of the gate dielectric layermay also be removed from above the top surface of the planarizationdielectric layer 60. Remaining portions of the gate dielectric layer andthe conductive material layer fill the gate cavities 59 and thetrench(es) 69.

A remaining portion of the gate dielectric layer in a gate cavity 59that is not connected to a trench 69 is herein referred to as afirst-type gate dielectric 50. A remaining portion of the conductivematerial layer in a gate cavity 59 that is not connected to a trench 69is herein referred to as a first-type gate electrode 54. A contiguousremaining portion of the gate dielectric layer that is present in atrench 69 and at least one gate cavity 59 is herein referred to as asecond-type gate dielectric 51. A contiguous remaining portion of theconductive material layer that is present in a trench 69 and at leastone gate cavity 59 is herein referred to as a second-type gate electrode58. Each stack of a first-type gate dielectric 50 and a first-type gateelectrode 54 constitutes a first-type replacement gate stack structure(50, 54), which is a gate stack structure including a replacement gateelectrode. Each stack of a second-type gate dielectric 51 and asecond-type gate electrode 58 constitutes a second-type replacement gatestack structure (51, 58), which is a gate stack structure including areplacement gate electrode. The first-type replacement gate stackstructures (50, 54) and the second-type replacement gate stackstructures (51, 58) are herein collectively referred to as replacementgate stack structures (50, 51, 54, 58). In one embodiment, all verticalportions of the first-type gate dielectric 50 and the second-type gatedielectric 51 can have the same thickness t. In one embodiment, allvertical portions and all horizontal portions of the first-type gatedielectric 50 and the second-type gate dielectric 51 can have the samethickness t.

The replacement gate stack structures (50, 51, 54, 58) can besimultaneously formed within the gate cavities 59 and the trench(es) 69.The replacement gate stack structures (50, 51, 54, 58) are embedded inthe planarization dielectric layer 60. Each replacement gate stackstructure (50, 51, 54, 58) includes a gate dielectric (50, 51) and agate electrode (54, 58) that is embedded in the gate dielectric (50,51). Each gate dielectric (50, 51) can include a horizontal portion incontact with a body region 32 and a vertical portion having outersidewalls that define a lateral extent of the replacement gate stackstructure (50, 51, 54, 58).

The first exemplary semiconductor structure includes interconnectedfield effect transistors. The first exemplary semiconductor structureincludes at least a semiconductor material portion (i.e., one of theplurality of semiconductor fins (32, 36, 36′)) including a source region(one of the source/drain regions 36), a drain region (another of thesource drain regions 36), and a body region 32 and located on asubstrate that includes the handle substrate 10 and the buried insulatorlayer 20. The planarization dielectric layer 60 overlies thesemiconductor material portion. A second-type gate stack structure (51,58) is embedded in the planarization dielectric layer 60 and including asecond-type gate dielectric 51 and a second-type gate electrode 58 thatis embedded in the second-type gate dielectric 51. The second-type gatedielectric 51 includes a horizontal portion 51H1 in contact with thebody region 32 and a vertical portion having outer sidewalls that definea lateral extent of the second-type gate stack structure (51, 58).

The second-type gate stack structure (51, 58) includes a first portionP1 contacting the semiconductor material portion and extending along afirst horizontal direction (i.e., the lengthwise direction of thefirst-type gate stack structures (50, 54)) and a second portion P2extending along a second horizontal direction that is different from thefirst direction. The second horizontal direction may, or may not, beorthogonal to the first direction. In one embodiment, the second portionP2 does not overlie the semiconductor material portion, and is laterallyoffset, i.e., is spaced, from the semiconductor material portion.

Each of the first-type and second-type gate dielectrics (50, 51) caninclude a dielectric metal oxide having a dielectric constant greaterthan 8.0. The second-type gate dielectric 51 in the second portion P2can further include another horizontal portion 51H2 that is verticallyoffset relative to the horizontal portion 51H1 that contacts the bodyregion 32. In one embodiment, a bottom surface of the other horizontalportion 51H2 can be in contact with a horizontal surface of theplanarization dielectric layer 60 that is located at a height between atopmost surface of the planarization dielectric layer 60 and abottommost surface of the planarization dielectric layer 60. In oneembodiment, semiconductor material portion can be a semiconductor fin(32, 36, 36′) located on a buried insulator layer 20 in the substrate(10, 20), and the bottom surface of the other horizontal portion 51H2can be located in a horizontal plane located beneath a horizontal planeincluding a topmost surface of the semiconductor fin (32, 36, 36′). Inanother embodiment, semiconductor material portion is a semiconductorfin (32, 36, 36′) located on a buried insulator layer 20 in thesubstrate 910, 20), and the bottom surface of the other horizontalportion 51H2 can be located in a horizontal plane located above ahorizontal plane including a topmost surface of the semiconductor fin(32, 36, 36′).

Referring to FIGS. 9A, 9B, and 9C, a contact-level dielectric layer 80can be deposited over the planarization dielectric layer 60. Variouscontact via structures can be formed through the contact-leveldielectric layer 80. The various contact via structures can include, forexample, gate contact via structures 85 that extend through thecontact-level dielectric layer 80 and contact one of the gate electrodes(54, 58), and active region contact via structures 86 that extendthrough a stack of the contact-level dielectric layer 80 and theplanarization dielectric layer 60 and contact the source/drain regions36. Optionally, at least one metal semiconductor alloy portions (notshown) can be formed between the contact via structures (85, 86) and thesource/drain regions 36 or gate electrodes (54, 58).

Referring to FIG. 10, a second exemplary semiconductor structure can bederived from the first exemplary semiconductor structure by increasingthe depth of the trench(es) 69. In this case, a semiconductor materialportion (e.g., one of the semiconductor fins (32, 36, 36′)) can belocated on the buried insulator layer 20, and a bottom surface of theother horizontal portion 51H2 of the second-type gate dielectric 51 canbe in contact with a surface of the buried insulator layer 20. In oneembodiment, the bottom surface of the other horizontal portion 51H2 canbe coplanar with a topmost surface of the buried insulator layer 20.

Referring to FIG. 11, a third exemplary semiconductor structure can bederived from the first exemplary semiconductor structure by increasingthe depth of the trench(es) 69. In this case, a semiconductor materialportion (e.g., one of the semiconductor fins (32, 36, 36′)) can belocated on the buried insulator layer 20, and a bottom surface of theother horizontal portion 51H2 of the second-type gate dielectric 51 canbe in contact with a surface of the buried insulator layer 20. In oneembodiment, the bottom surface of the other horizontal portion 51H2 canbe located below a topmost surface of the buried insulator layer 20.

While the disclosure has been described in terms of specificembodiments, it is evident in view of the foregoing description thatnumerous alternatives, modifications and variations will be apparent tothose skilled in the art. Each of the various embodiments of the presentdisclosure can be implemented alone, or in combination with any otherembodiments of the present disclosure unless expressly disclosedotherwise or otherwise impossible as would be known to one of ordinaryskill in the art. Accordingly, the disclosure is intended to encompassall such alternatives, modifications and variations which fall withinthe scope and spirit of the disclosure and the following claims.

What is claimed is:
 1. A method of forming a semiconductor structurecomprising: forming at least one semiconductor material portion on asubstrate; forming at least one disposable gate structure over said atleast one semiconductor material portion; forming a planarizationdielectric layer over said at least one semiconductor material portionand said at least one disposable gate structure; forming a trench insaid planarization dielectric layer, wherein a sidewall of a remainingportion of one of said at least one disposable gate structure isphysically exposed within said trench; forming at least one gate cavityby removing said at least one disposable gate structure; and forming areplacement gate stack structure in said at least one gate cavity andsaid trench.
 2. The method of claim 1, wherein said replacement gatestack structure is embedded in said planarization dielectric layer andincludes a gate dielectric and a gate electrode that is embedded in saidgate dielectric.
 3. The method of claim 2, wherein said gate dielectricincludes a horizontal portion in contact with said body region and avertical portion having outer sidewalls that define a lateral extent ofsaid replacement gate stack structure.
 4. The method of claim 1, whereinsaid at least one disposable gate structure extends along a firsthorizontal direction, and said trench extends along a second directionthat is different from said first direction.
 5. The method of claim 1,wherein a sidewall of a remaining portion of another of said at leastone disposable gate structure is physically exposed within said trench.6. The method of claim 1, further comprising forming a gate spaceraround each of said at least one disposable gate structure prior toforming said planarization dielectric layer, wherein a portion of one ofsaid gate spacer that is formed on said one of said at least onedisposable gate structure is physically removed during said forming ofsaid trench.
 7. The method of claim 1, wherein a bottom surface of saidtrench comprises a recessed surface of said planarization dielectriclayer.
 8. The method of claim 1, wherein said substrate comprises aburied insulator layer, and a bottom surface of said trench is arecessed surface of said insulator layer.
 9. The method of claim 1,wherein said substrate comprises a buried insulator layer, and saidmethod further comprising forming a gate spacer around each of said atleast one disposable gate structure and on a top surface of said buriedinsulator layer prior to forming said planarization dielectric layer,wherein at least an upper portion of one of said gate spacer is removedduring said forming of said trench.